The body of a young humpback whale washed ashore on Marajó Island in Brazil — and it ended up nearly 50 feet (15 meters) inland near the mouth of the Amazon river, according to a Facebook post from the wildlife nonprofit group Bicho D'água.

This humpback is not as big as it appears in the photos, only about 26 feet (8 m) long, they wrote. Because full-grown humpback whales can reach over twice that size, this whale is thought to be only about a year old. [In Photos: Tracking Humpback Whales]

Not much is known about how the whale died or what population of whales it belonged to, but researchers from the institute are working to collect biological samples to resolve these and other related mysteries, according to an Instagram post from the group.

In any case, this young one seems to have gotten very lost.

It's uncommon to find humpbacks around Marajó Island, said Alex Zerbini, a wildlife biologist with the Marine Mammal Laboratory of the NOAA Fisheries in Seattle. This whale could belong to one of two populations of humpbacks: the western South Atlantic humpbacks or the North Atlantic humpbacks, he said.

While the western South Atlantic humpbacks do breed off northeast Brazil, it's "not the right time for this population" to be nearby, Zerbini said. At this time of year, they are farther down near south Georgia and South Sandwich Islands. They migrate up to breed between June and November, he said. "But it is possible that an animal got lost during breeding season [last year]," and never made it down to the feeding grounds, he said.

It's more likely that the animal belonged to the North Atlantic humpback population that typically breed in tropical waters at this time of year, in the Caribbean and off Venezuela, he said.

Whales typically strand after getting sick and becoming disoriented, he said. Once disoriented, in this case, the whale may have been pushed ashore by high tides, he said. It's not known whether the whale was alive when it was pushed ashore.

Tides in that region can reach over 7 meters (23 feet) — and last week's huge full-moon-driven tides could have "easily" pushed the whale 50 feet inland, said Milton Marcondes, a research coordinator at the Humpback Whale Institute in Brazil. "This is not the first stranding of humpback whales in the region, but it's a rare event," Marcondes said. That being said, because the number of humpbacks around Brazil is increasing, strandings would also go up, he said.

Indeed, both the South Atlantic and North Atlantic populations have been recovering greatly from decades of whaling, Zerbini said. With now-robust numbers of humpbacks, "it is very likely that these kinds of occurrences are going to be more common from now on."

Originally published on Live Science.